1. Technical Field
The invention relates to an optical scanner, a mirror chip, a method of manufacturing an optical scanner, and an image forming apparatus.
2. Related Art
As an example of an optical scanner which performs drawing by light scanning in a laser printer or the like, an optical scanner which is formed by a torsional oscillator and which uses an actuator is known (for example, refer to JP-A-2005-181395).
JP-A-2005-181395 discloses an actuator including an insulating substrate, in which a pair of permanent magnets is provided, and a scanner body, which is supported on the insulating substrate so as to be located between the pair of permanent magnets. In addition, the scanner body has a frame-like support section, a frame-like outer movable plate provided inside the support section, and an inner movable plate (mirror) provided inside the outer movable plate. In addition, the outer movable plate is connected to the support section through a pair of first torsion bars which extends in the X-axis direction, and the inner movable plate is connected to the outer movable plate through a second torsion bar which extends in the Y-axis direction crossing the X-axis direction. In addition, a coil is provided in each of the outer movable plate and the inner movable plate.
In the actuator with such a configuration, a magnetic field generated from each coil by application of an electric current and a magnetic field generated between the pair of permanent magnets act. As a result, the outer movable plate rotates around the X axis together with the inner movable plate with the first torsion bar as a central axis, and the inner movable plate rotates around the Y axis with the second torsion bar as a central axis.
Thus, in the actuator disclosed in JP-A-2005-181395, the mechanism for rotating the inner movable plate around the X axis is different from the mechanism for rotating the inner movable plate around the Y axis. For this reason, it is not possible to rotate the inner movable plate around the X and Y axes under the same conditions. In addition, in the actuator disclosed in JP-A-2005-181395, the magnetic field generated from the coil provided in the outer movable plate and the magnetic field generated from the coil provided in the inner movable plate interfere with each other. For this reason, it is not possible to rotate the inner movable plate independently around each of the X and Y axes. Accordingly, in the actuator disclosed in JP-A-2005-181395, there is a problem in that it is not possible to rotate the inner movable plate stably around each of the X and Y axes.